Catalyst component for the preparation of nucleated polyolefins

ABSTRACT

Catalyst composition comprising a phthalate-free electron donor, which is highly effective during polymerisation in the presence of a polymeric nucleating agent, and its use and a process for its preparation.

The invention relates to a phthalate-free catalyst composition,particularly one comprising a Group 2 metal.

The invention also relates to the use of such a catalyst compositionwhich can be further used in the polymerisation of alpha-olefins, likee.g. polyethylene and polypropylene, comprising nucleating agents.

It further relates to a process for preparing a nucleated polypropylenebased on above said phthalate-free catalyst composition.

BACKGROUND OF THE INVENTION

Ziegler-Natta (ZN) type polyolefin catalysts are well known in the fieldof polymers, generally, they comprise (a) at least a catalyst componentformed from a transition metal compound of Group 4 to 6 of the PeriodicTable (IUPAC, Nomenclature of Inorganic Chemistry, 1989), a metalcompound of Group 1 to 3 of the Periodic Table (IUPAC), and, optionally,a compound of group 13 of the Periodic Table (IUPAC) and/or an internaldonor compound. ZN catalyst may also comprise (b) further catalystcomponent(s), such as a cocatalyst and/or an external donor.

Various methods for preparing ZN catalysts are known in the state ofart. In one known method, a supported ZN catalyst system is prepared byimpregnating the catalyst components on a particulate support material.In WO-A-01 55 230, the catalyst component(s) are supported on a porous,inorganic or organic particulate carrier material, such as silica.

In a further well known method the carrier material is based on one ofthe catalyst components, e.g. on a magnesium compound, such as MgCl₂.This type of carrier material can also be formed in various ways.EP-A-713 886 of Japan Olefins describes the formation of MgCl₂ adductwith an alcohol which is then emulsified and finally the resultantmixture is quenched to cause the solidification of the droplets.Alternatively, EP-A-856 013 of BP discloses the formation of a solidMg-based carrier, wherein the Mg-component containing phase is dispersedto a continuous phase and the dispersed Mg-phase is solidified by addingthe two-phase mixture to a liquid hydrocarbon. The formed solid carrierparticles are normally treated with a transition metal compound andoptionally with other compounds for forming the active catalyst.

Accordingly, in case of external carriers, some examples of which aredisclosed above, the morphology of the carrier is one of the definingfactors for the morphology of the final catalyst.

WO-A-00 08073 and WO-A-00 08074 describe further methods for producing asolid ZN-catalyst, wherein a solution of an Mg-based compound and one ormore further catalyst compounds are formed and the reaction productthereof is precipitated out of the solution by heating the system.Furthermore, EP-A-926 165 discloses another precipitating method,wherein a mixture of MgCl₂ and Mg-alkoxide is precipitated together witha Ti-compound to give a ZN catalyst.

EP-A-83 074 and EP-A-83 073 of Montedison disclose methods for producinga ZN catalyst or a precursor thereof, wherein an emulsion or dispersionof Mg and/or Ti compound is formed in an inert liquid medium or inertgas phase and said system is reacted with an Al-alkyl compound toprecipitate a solid catalyst. According to examples said emulsion isthen added to a larger volume of Al-compound in hexane andprepolymerised to cause the precipitation.

In polymerisation process this causes in turn undesired and harmfuldisturbances, like plugging, formation of polymer layer on the walls ofthe reactor and in lines and in further equipments, like extruders, aswell decreased flowability of polymer powder and other polymer handlingproblems.

EP 1403292 A1, EP 0949280 A1, U.S. Pat. Nos. 4,294,948, 5,413,979 and5,409,875 as well as EP 1273595 A1 describe processes for thepreparation of olefin polymerisation catalyst components or olefinpolymerisation catalysts as well as processes for preparing olefinpolymers or copolymers.

Accordingly, although much development work has been done in the fieldof Ziegler-Natta catalysts, there remains a need for alternative orimproved methods of producing ZN catalysts with desirable properties.One particular aspect in this connection is the desire to avoid as faras possible the use of substances which are considered as potentialharmful compounds regarding health as well as environmental aspects. Oneclass of substances which have been considered as potential harmfulcompounds is phthalates, which have been commonly used as internalelectron donors in Ziegler-Natta type catalysts.

Although the amount of these phthalate compounds, used as internaldonors in catalysts, in the final polymer is very small, it is stilldesirable to find out alternative compounds to replace phthalatecompounds and still get catalysts having good activity, excellentmorphology and other desired properties.

WO-1999024478-A1 discloses a polymerisation method to incorporatepolymeric nucleating agents into the polymer to modify the mechanicalproperties.

This process is based on Ziegler-Natta catalysts as mentioned above,which comprise an internal donor based on phthalate-compositions.

However, some of such phthalate-compositions are under suspicion ofgenerating negative HSE effects Furthermore, there is an increasingdemand on the market for “phthalate-free polypropylene” suitable forvarious applications, e.g. in the field of packaging and medicalapplications as well as personal care, or personal hygiene.

WO2012007430 also incorporated herein by reference, is one example of alimited number of patent applications, describing phthalate freecatalysts based on citraconate as internal donor.

However, up to now the mechanical properties of polypropylenes producedwith catalysts having citraconate compositions as internal donors didnot fulfill all the desired requirements, especially in view ofstiffness/impact-balance. Up to now significantly higher amount ofinternal donor is to be used in the phthalate-free catalyst preparationto achieve the desired polymer properties

Although the inventors of WO2012007430 considered adding donor dissolvedin organic solvent and TiCl4 to form washing solution, the reactivity ofsuch catalyst is not satisfying in respect to activity (being low), orxylene solubles (being high).

Object of the Invention

So the present invention concerns a catalyst composition, which isespecially suitable for the production of nucleated polypropylenecompositions.

In a special embodiment the present invention deals also with the use ofabove mentioned catalyst composition in polymerisation processes,suitable for the production of nucleated polypropylene comprising apolymeric nucleating agent.

In a further embodiment the present invention is related a process forthe production of nucleated polypropylene in the presence of a polymericnucleating agent and a phthalate free catalyst component.

A catalyst having high nucleating effect in polypropylene, is of outmostimportance when polyolefins, especially polypropylenes with improvedstiffness-impact behaviour are desired, as a good nucleation hasdecisive effect on the performance of the final product.

Surprisingly the inventors have now identified a catalyst compositionwhich solves the above identified problems.

Thus the present invention provides a catalyst composition containing acatalyst component obtained by a process comprising the steps of

-   a1) providing a solution of at least a Group 2 metal alkoxy compound    (Ax) being the reaction product of a Group 2 metal compound (MC) and    a monohydric alcohol (A) comprising in addition to the hydroxyl    moiety at least one ether moiety optionally in an organic liquid    reaction medium; or-   a2) a solution of at least a Group 2 metal alkoxy compound (Ax′)    being the reaction product of a Group 2 metal compound (MC) and an    alcohol mixture of the monohydric alcohol (A) and a monohydric    alcohol (B) of formula ROH, optionally in an organic liquid reaction    medium; or-   a3) providing a solution of a mixture of the Group 2 metal alkoxy    compound (Ax) and a Group 2 metal alkoxy compound (Bx) being the    reaction product of a Group 2 metal compound (MC) and the monohydric    alcohol (B), optionally in an organic liquid reaction medium; or-   a4) providing a solution of Group 2 metal alkoxy compound of formula    M(OR1)_(n)(OR₂)_(mX2−n−m) or mixture of Group 2 alkoxides    M(OR1)_(n′X2−n′) and M(OR2)_(m′X2−m′), where M is Group 2 metal, X    is halogen, R1 and R2 are different alkyl groups of C2 to C16 carbon    atoms, and 0≤n<2, 0≤m<2 and n+m+(2−n−m)=2, provided that both n and    m≠0, 0<n′≤2 and 0<m′≤2;-   and-   b) adding said solution from step a) to at least one compound (TC)    of a transition metal of Group 4 to 6 and-   c) obtaining the solid catalyst component particles,-   d) washing said solidified particles,-   e) recovering the solidified particles of the olefin polymerisation    catalyst component, wherein an electron donor is added at any step    prior to step c) and is a non-phthalic internal electron donor,-   and wherein the catalyst component is further modified by a    polymeric nucleating agent comprising vinyl compound units.

The present invention is further related to the use of the abovemodified catalyst component together with a cocatalyst and optionally anexternal donor for the production of polyolefins, like e.g. polyethyleneand polypropylene and their copolymers, especially of nucleatedpolypropylenes; as the catalyst of the present invention has a highnucleating efficiency and The present invention is also related to theprocess for producing nucleated polypropylene.

The catalyst composition produced according the current invention hasalso very high reactivity towards polymeric nucleating agents and showshigher conversion of polymeric nucleating agents, namely lower levels ofunreacted VCH than prior art catalysts. This again has decisive effecton the performance of the final product.

The catalyst composition of the present inventions also fulfills boththe expected future legal and HSE-requirements regarding phthalate freecatalyst systems.

The advantages of the present polymerisation method can especially beseen in the increased crystallinity (i.e. increase of theCrystallisation temperature Tcr) of the produced polypropylene.

There is also an increase seen in the Melting Temperature (Tm) of thenucleated polypropylene produced with this catalyst composition.

The present polymerisation method provides nucleated polypropyleneproducts comprising polymeric nucleating agents like vinyl compoundsselected from the group of vinyl alkanes, vinyl cyclo alkanes, likevinyl cyclohexane, vinyl cyclopentane, vinyl-2-methyl cyclohexane andvinyl norbornane, 3methyl-1-butene, styrene, p-methyl-styrene,3-ethyl-1-hexene and mixtures thereof, wherein vinyl alkanes or vinylcycyloalkanes are espcecially preferred.

Said polypropylene products have increased crystallinity and henceimproved stiffness/impact behaviour.

DETAILED DESCRIPTION OF THE INVENTION

Catalyst Description

The Ziegler-Natta catalyst (ZN-C) will be now described in more detail.

The catalyst used in the present invention is a solid Ziegler-Nattacatalyst (ZN-C), which comprises compounds (TC) of a transition metal ofGroup 4 to 6 of IUPAC, like titanium, a Group 2 metal compound (MC),like a magnesium, and an internal donor (ID) being a non-phthaliccompound, preferably a non-phthalic acid ester, still more preferablybeing a diester of non-phthalic dicarboxylic acids as described in moredetail below. Thus, the catalyst is fully free of undesired phthaliccompounds. Further, the solid catalyst is free of any external supportmaterial, like silica or MgCl₂, but the catalyst is selfsupported.

The Ziegler-Natta catalyst (ZN-C) can be further defined by the way asobtained.

Accordingly, the Ziegler-Natta catalyst (ZN-C) is preferably obtained bya process comprising the steps of

-   a)    -   a₁) providing a solution of at least a Group 2 metal alkoxy        compound (Ax) being the reaction product of a Group 2 metal        compound (MC) and a monohydric alcohol (A) comprising in        addition to the hydroxyl moiety at least one ether moiety        optionally in an organic liquid reaction medium; or    -   a₂) a solution of at least a Group 2 metal alkoxy compound (Ax′)        being the reaction product of a Group 2 metal compound (MC) and        an alcohol mixture of the monohydric alcohol (A) and a        monohydric alcohol (B) of formula ROH, optionally in an organic        liquid reaction medium; or    -   a₃) providing a solution of a mixture of the Group 2 metal        alkoxy compound (Ax) and a Group 2 metal alkoxy compound (Bx)        being the reaction product of a Group 2 metal compound (MC) and        the monohydric alcohol (B), optionally in an organic liquid        reaction medium; or    -   a₄) providing a solution of Group 2 metal alkoxy compound of        formula M(OR₁)_(n)(OR₂)_(m)X_(2−n−m) or mixture of Group 2        alkoxides M(OR₁)_(n′)X_(2−n), and M(OR₂)_(m′)X_(2−m′), where M        is Group 2 metal, X is halogen, R₁ and R₂ are different alkyl        groups of C₂ to C₁₆ carbon atoms, and 0≤n<2, 0≤m<2 and        n+m+(2−n−m)=2, provided that both n and m≠0, 0<n′≤2 and 0≤m′≤2;        and-   b) adding said solution from step a) to at least one compound (TC)    of a transition metal of Group 4 to 6 and-   c) obtaining the solid catalyst component particles,-   and adding a non-phthalic internal electron donor (ID) at any step    prior to step c).

The internal donor (ID) or precursor thereof is thus added preferably tothe solution of step a) or to the transition metal compound beforeadding the solution of step a).

According to the procedure above the Ziegler-Natta catalyst (ZN-C) canbe obtained via precipitation method or via emulsion—solidificationmethod depending on the physical conditions, especially temperature usedin steps b) and c). Emulsion is also called in this applicationliquid/liquid two-phase system.

In both methods (precipitation or emulsion-solidification) the catalystchemistry is the same.

In precipitation method combination of the solution of step a) with atleast one transition metal compound (TC) in step b) is carried out andthe whole reaction mixture is kept at least at 50° C., more preferablyin the temperature range of 55 to 110° C., more preferably in the rangeof 70 to 100° C., to secure full precipitation of the catalyst componentin form of a solid particles (step c).

In emulsion—solidification method in step b) the solution of step a) istypically added to the at least one transition metal compound (TC) at alower temperature, such as from −10 to below 50° C., preferably from −5to 30° C. During agitation of the emulsion the temperature is typicallykept at −10 to below 40° C., preferably from −5 to 30° C. Droplets ofthe dispersed phase of the emulsion form the active catalystcomposition. Solidification (step c) of the droplets is suitably carriedout by heating the emulsion to a temperature of 70 to 150° C.,preferably to 80 to 110° C.

The catalyst prepared by emulsion—solidification method is preferablyused in the present invention.

In a preferred embodiment in step a) the solution of a₂) or a₃) areused, i.e. a solution of (Ax′) or a solution of a mixture of (Ax) and(Bx), especially the solution of a₂).

Preferably the Group 2 metal (MC) is magnesium.

The magnesium alkoxy compounds as defined above can be prepared in situin the first step of the catalyst preparation process, step a), byreacting the magnesium compound with the alcohol(s) as described above,or said magnesium alkoxy compounds can be separately prepared magnesiumalkoxy compounds or they can be even commercially available as readymagnesium alkoxy compounds and used as such in the catalyst preparationprocess of the invention.

Illustrative examples of alcohols (A) are glycol monoethers. Preferredalcohols (A) are C₂ to C₄ glycol monoethers, wherein the ether moietiescomprise from 2 to 18 carbon atoms, preferably from 4 to 12 carbonatoms. Preferred examples are 2-(2-ethylhexyloxy)ethanol, 2-butyloxyethanol, 2-hexyloxy ethanol and 1,3-propylene-glycol-monobutyl ether,3-butoxy-2-propanol, with 2-(2-ethylhexyloxy)ethanol and1,3-propylene-glycol-monobutyl ether, 3-butoxy-2-propanol beingparticularly preferred.

Illustrative monohydric alcohols (B) are of formula ROH, with R beingstraight-chain or branched C₂-C₁₆ alkyl residue, preferably C₄ to C₁₀,more preferably C6 to C₈ alkyl residue. The most preferred monohydricalcohol is 2-ethyl-1-hexanol or octanol.

Preferably a mixture of Mg alkoxy compounds (Ax) and (Bx) or mixture ofalcohols (A) and (B), respectively, are used and employed in a moleratio of Bx:Ax or B:A from 10:1 to 1:10, more preferably 6:1 to 1:6,most preferably 4.1 to 1:4.

Magnesium alkoxy compound may be a reaction product of alcohol(s), asdefined above, and a magnesium compound selected from dialkylmagnesiums, alkyl magnesium alkoxides, magnesium dialkoxides, alkoxymagnesium halides and alkyl magnesium halides. Further, magnesiumdialkoxides, magnesium diaryloxides, magnesium aryloxyhalides, magnesiumaryloxides and magnesium alkyl aryloxides can be used. Alkyl groups canbe a similar or different C₁-C₂₀ alkyl, preferably C₂-C₁₀ alkyl. Typicalalkyl-alkoxy magnesium compounds, when used, are ethyl magnesiumbutoxide, butyl magnesium pentoxide, octyl magnesium butoxide and octylmagnesium octoxide. Preferably the dialkyl magnesiums are used. Mostpreferred dialkyl magnesiums are butyl octyl magnesium or butyl ethylmagnesium.

It is also possible that magnesium compound can react in addition to thealcohol (A) and alcohol (B) also with a polyhydric alcohol (C) offormula R″ (OH)_(m) to obtain said magnesium alkoxide compounds.Preferred polyhydric alcohols, if used, are alcohols, wherein R″ is astraight-chain, cyclic or branched C₂ to C₁₀ hydrocarbon residue, and mis an integer of 2 to 6.

The magnesium alkoxy compounds of step a) are thus selected from thegroup consisting of magnesium dialkoxides, diaryloxy magnesiums,alkyloxy magnesium halides, aryloxy magnesium halides, alkyl magnesiumalkoxides, aryl magnesium alkoxides and alkyl magnesium aryloxides. Inaddition a mixture of magnesium dihalide and a magnesium dialkoxide canbe used.

The solvents to be employed for the preparation of the present catalystmay be selected among aromatic and aliphatic straight chain, branchedand cyclic hydrocarbons with 5 to 20 carbon atoms, more preferably 5 to12 carbon atoms, or mixtures thereof. Suitable solvents include benzene,toluene, cumene, xylene, pentane, hexane, heptane, octane and nonane.

Hexanes and pentanes are particular preferred.

The reaction for the preparation of the magnesium alkoxy compound may becarried out at a temperature of 40° to 70° C. Most suitable temperatureis selected depending on the Mg compound and alcohol(s) used.

The transition metal compound of Group 4 to 6 is preferably a titaniumcompound, most preferably a titanium halide, like TiCl₄.

The internal donor (ID) used in the preparation of the catalyst used inthe present invention is preferably selected from (di)esters ofnon-phthalic carboxylic (di)acids, 1,3-diethers, derivatives andmixtures thereof. Especially preferred donors are diesters ofmono-unsaturated dicarboxylic acids, in particular esters belonging to agroup comprising malonates, maleates, succinates, citraconates,glutarates, cyclohexene-1,2-dicarboxylates and benzoates, and anyderivatives and/or mixtures thereof. Preferred examples are e.g.substituted maleates and citraconates, most preferably citraconates.

In emulsion method, the two phase liquid-liquid system may be formed bysimple stirring and optionally adding (further) solvent(s) andadditives, such as the turbulence minimizing agent (TMA) and/or theemulsifying agents and/or emulsion stabilizers, like surfactants, whichare used in a manner known in the art for facilitating the formation ofand/or stabilize the emulsion. Preferably, surfactants are acrylic ormethacrylic polymers. Particular preferred are unbranched C₁₂ to C₂₀(meth)acrylates such as poly(hexadecyl)-methacrylate andpoly(octadecyl)-methacrylate and mixtures thereof. Turbulence minimizingagent (TMA), if used, is preferably selected from α-olefin polymers ofα-olefin monomers with 6 to 20 carbon atoms, like polyoctene,polynonene, polydecene, polyundecene or polydodecene or mixturesthereof. Most preferable it is polydecene.

The solid particulate product obtained by precipitation oremulsion—solidification method may be washed at least once, preferablyat least twice, most preferably at least three times with an aromaticand/or aliphatic hydrocarbons, preferably with toluene, heptane orpentane and or with TiCl₄. Washing solutions can also contain donorsand/or compounds of Group 13, like trialkyl aluminium, halogenated alkyaluminium compounds or alkoxy aluminium compounds.

Aluminium compounds can also be added during the catalyst synthesis. Thecatalyst can further be dried, as by evaporation or flushing withnitrogen or it can be slurried to an oily liquid without any dryingstep.

Preferably the catalyst component is washed at least three times with atleast one toluene and at least one TiCl4 washing step and 1 to 3 furtherwashing steps with an aromatic and/or aliphatic hydrocarbons selectedfrom toluene, heptane or pentane.

In a further preferred embodiment donor is added to either a toluenewash step and/or to a TiCl4 wash step.

The amount of donor added to the washing steps is in the range of 10 to60 wt % of the total amount of donor used in catalyst preparation stepsa) to d).

In case there are more than one washing step where donor is added, theamount of donor in each of the according washing steps may be in therange of at least of 5-55 wt % of the total amount of donor used incatalyst preparation steps a) to d), wherein the amount of donor addedto the washing steps is in the range of 10 to 60 wt % of the totalamount of donor used in catalyst preparation steps a) to d).

The finally obtained Ziegler-Natta catalyst component is desirably inthe form of particles having generally an average particle size range of5 to 200 μm, preferably 10 to 100. Particles are compact with lowporosity and have surface area below 20 g/m², more preferably below 10g/m². Typically the amount of Ti is 1 to 6 wt-%, Mg 8 to 20 wt-% anddonor 10 to 40 wt-% of the catalyst composition.

Detailed description of preparation of catalysts is disclosed in WO2012/007430, EP2610271, EP 2610270 and EP2610272 which are incorporatedhere by reference.

The Ziegler-Natta catalyst (ZN-C) is preferably used in association withan alkyl aluminum cocatalyst and external donors.

Suitable external donors (ED) include certain silanes, ethers, esters,amines, ketones, heterocyclic compounds and blends of these. It isespecially preferred to use a silane. It is most preferred to usesilanes of the general formulaR^(a) _(p)R^(b) _(q)Si(OR^(c))_((4−p−q))wherein R^(a), R^(b) and R^(c) denote a hydrocarbon radical, inparticular an alkyl or cycloalkyl group, and wherein p and q are numbersranging from 0 to 3 with their sum p+q being equal to or less than 3.R^(a), R^(b) and R^(c) can be chosen independently from one another andcan be the same or different. Specific examples of such silanes are(tert-butyl)₂Si(OCH₃)₂, (cyclohexyl)(methyl)Si(OCH₃)²,(phenyl)₂Si(OCH₃)₂ and (cyclopentyl)₂Si(OCH₃)₂, or of general formulaSi(OCH₂CH₃)₃(NR³R⁴)wherein R³ and R⁴ can be the same or different a represent a hydrocarbongroup having 1 to 12 carbon atoms.

R³ and R⁴ are independently selected from the group consisting of linearaliphatic hydrocarbon group having 1 to 12 carbon atoms, branchedaliphatic hydrocarbon group having 1 to 12 carbon atoms and cyclicaliphatic hydrocarbon group having 1 to 12 carbon atoms. It is inparticular preferred that R³ and R⁴ are independently selected from thegroup consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl,iso-propyl, iso-butyl, iso-pentyl, tert.-butyl, tert.-amyl, neopentyl,cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

More preferably both R¹ and R² are the same, yet more preferably both R³and R⁴ are an ethyl group.

Especially preferred external donors (ED) are thedi-cyclopentyl-dimethoxy silane donor (D-donor) or the cyclohexylmethyldimethoxy silane donor (C-Donor).

In addition to the Ziegler-Natta catalyst (ZN-C) and the optionalexternal donor (ED) a co-catalyst can be used. The co-catalyst ispreferably a compound of group 13 of the periodic table (IUPAC), e.g.organo aluminum, such as an aluminum compound, like aluminum alkyl,aluminum halide or aluminum alkyl halide compound. Accordingly, in onespecific embodiment the co-catalyst (Co) is a trialkylaluminium, liketriethylaluminium (TEAL), dialkyl aluminium chloride or alkyl aluminiumdichloride or mixtures thereof. In one specific embodiment theco-catalyst (Co) is triethylaluminium (TEAL).

Advantageously, the triethyl aluminium (TEAL) has a hydride content,expressed as AlH₃, of less than 1.0 wt % with respect to the triethylaluminium (TEAL). More preferably, the hydride content is less than 0.5wt %, and most preferably the hydride content is less than 0.1 wt %.

Preferably the ratio between the co-catalyst (Co) and the external donor(ED) [Co/ED] and/or the ratio between the co-catalyst (Co) and thetransition metal (TM) [Co/TM] should be carefully chosen.

Accordingly,

-   -   (a) the mol-ratio of co-catalyst (Co) to external donor (ED)        [Co/ED] must be in the range of 5 to 45, preferably is in the        range of 5 to 35, more preferably is in the range of 5 to 25;        and optionally    -   (b) the mol-ratio of co-catalyst (Co) to titanium compound (TC)        [Co/TC] must be in the range of above 80 to 500, preferably is        in the range of 100 to 350, still more preferably is in the        range of 120 to 300.

According to the present invention the catalyst component is modifiedwith a polymeric nucleating agent.

Any known polymeric nucleating agent may be employed including polymersof vinyl alkanes and vinyl cycloalkanes.

A preferred example of such a polymeric nucleating agent is a vinylpolymer, such as a vinyl polymer derived from monomers of the formulaCH2=CH—CHR1R2wherein R1 and R2, together with the carbon atom they are attached to,form an optionally substituted saturated or unsaturated or aromatic ringor a fused ring system, wherein the ring or fused ring moiety containsfour to 20 carbon atoms, preferably 5 to 12 membered saturated orunsaturated or aromatic ring or a fused ring system or independentlyrepresent a linear or branched C4-C30 alkane, C4-C20 cycloalkane orC4-C20 aromatic ring. Preferably R1 and R2, together with the C-atomwherein they are attached to, form a five- or six-membered saturated orunsaturated or aromatic ring or independently represent a lower alkylgroup comprising from 1 to 4 carbon atoms. Preferred vinyl compounds forthe preparation of a polymeric nucleating agent to be used in accordancewith the present invention are in particular vinyl cycloalkanes, inparticular vinyl cyclohexane (VCH), vinyl cyclopentane, andvinyl-2-methyl cyclohexane, 3-methyl-1-butene, 3-ethyl-1-hexene,3-methyl-1-pentene, 4-methyl-1-pentene or mixtures thereof. VCH is aparticularly preferred monomer.

The polymeric nucleating agent is incorporated in the catalyst componentby the so called BNT-technology as mentioned below.

With regard to the BNT-technology reference is made to the internationalapplications WO 99/24478, WO 99/24479 and particularly WO 00/68315.According to this technology the catalyst component is modified bypolymerising a vinyl compound in the presence of the catalyst system,comprising in particular the special catalyst component, an externaldonor and a cocatalyst

General conditions for the modification of the catalyst, like liquidmedia and process parameters are also disclosed in WO 99/24478, WO99/24479 and particularly WO 00/68315, incorporated herein by referencewith respect to the modification of the polymerisation catalyst.

The weight ratio of vinyl compound to polymerisation catalyst in themodification step of the polymerisation catalyst preferably is 0.3 ormore up to 40, such as 0.4 to 20 or more preferably 0.5 to 15, like 0.5to 2.0.

Suitable media for the modification step include, in addition to oils,also aliphatic inert organic solvents with low viscosity, such aspentane and heptane. Furthermore, small amounts of hydrogen can be usedduring the modification.

The polymeric nucleating agent usually is present in the final productin an amount of from more than 10 ppm, typically more than 15 ppm,(based on the weight of the polypropylene composition). Preferably thisagent is present in the polypropylene composition in a range of from 10to 1000 ppm, more preferably more than 15 to 500 ppm, such as 20 to 100ppm.

The polymerisation of the catalyst with said vinyl compound is performeduntil the concentration of unreacted vinyl compound is less than about0.5 wt %, preferably less than 0.1 wt %.

This polymerisation step is usually done in the pre-polymerisation stepprior to the polymerisation process used for producing the polyolefin,especially for producing the nucleated polyolefin.

Prepolymerisation Details:

The preparation of the polyolefin polymers, especially the nucleatedpropylene polymer comprises in addition to the (main) polymerisation ofthe propylene polymer prior thereto a pre-polymerisation in apre-polymerisation reactor (PR) upstream to the first polymerisationreactor (R1).

In the pre-polymerisation reactor (PR) a polypropylene (Pre-PP) isproduced. The pre-polymerisation is conducted in the presence of themodified Ziegler-Natta catalyst (ZN-C). According to this embodiment themodified Ziegler-Natta catalyst (ZN-C), the co-catalyst (Co), and theexternal donor (ED) are all introduced to the pre-polymerisation step.However, this shall not exclude the option that at a later stage forinstance further co-catalyst (Co) and/or external donor (ED) is added inthe polymerisation process, for instance in the first reactor (R1). Inone embodiment the modified Ziegler-Natta catalyst (ZN-C), theco-catalyst (Co), and the external donor (ED) are only added in thepre-polymerisation reactor (PR).

The pre-polymerisation reaction is typically conducted at a temperatureof 0 to 60° C., preferably from 15 to 50° C., and more preferably from20 to 45° C.

The pressure in the pre-polymerisation reactor is not critical but mustbe sufficiently high to maintain the reaction mixture in liquid phase.Thus, the pressure may be from 20 to 100 bar, for example 30 to 70 bar.

In a preferred embodiment, the pre-polymerisation is conducted as bulkslurry polymerisation in liquid propylene, i.e. the liquid phase mainlycomprises propylene, with optionally inert components dissolved therein.Furthermore, according to the present invention, an ethylene feed can beemployed during pre-polymerisation as mentioned above.

It is possible to add other components also to the pre-polymerisationstage. Thus, hydrogen may be added into the pre-polymerisation stage tocontrol the molecular weight of the polypropylene (Pre-PP) as is knownin the art. Further, antistatic additive may be used to prevent theparticles from adhering to each other or to the walls of the reactor.

The precise control of the pre-polymerisation conditions and reactionparameters is within the skill of the art.

Due to the above defined process conditions in the pre-polymerisation, amixture (MI) of the modified Ziegler-Natta catalyst (ZN-C) and thepolypropylene (Pre-PP) produced in the pre-polymerisation reactor (PR)is obtained. Preferably the modified Ziegler-Natta catalyst (ZN-C) is(finely) dispersed in the polypropylene (Pre-PP). In other words, themodified Ziegler-Natta catalyst (ZN-C) particles introduced in thepre-polymerisation reactor (PR) split into smaller fragments which areevenly distributed within the growing polypropylene (Pre-PP). The sizesof the introduced modified Ziegler-Natta catalyst (ZN-C) particles aswell as of the obtained fragments are not of essential relevance for theinstant invention and within the skilled knowledge.

Accordingly, the propylene polymer is preferably produced in a processcomprising the following steps under the conditions set out above

In the pre-polymerisation, a mixture (MI) of the modified Ziegler-Nattacatalyst (ZN-C) and the polypropylene (Pre-PP) produced in thepre-polymerisation reactor (PR) is obtained.

Preferably the modified Ziegler-Natta catalyst (ZN-C) is (finely)dispersed in the polypropylene (Pre-PP). Subsequent to thepre-polymerisation, the mixture (MI) of the modified Ziegler-Nattacatalyst (ZN-C) and the polypropylene (Pre-PP) produced in thepre-polymerisation reactor (PR) is transferred to the first reactor(R1). Typically the total amount of the polypropylene (Pre-PP) in thefinal propylene copolymer (R-PP) is rather low and typically not morethan 5.0 wt.-%, more preferably not more than 4.0 wt.-%, still morepreferably in the range of 0.5 to 4.0 wt.-%, like in the range 1.0 of to3.0 wt.-%.

Polymerisation processes, where the catalyst components of the inventionare useful, comprise at least one polymerisation stage, wherepolymerisation is typically carried out in solution, slurry, bulk or gasphase. Typically, the polymerisation process comprises additionalpolymerisation stages or reactors.

In one particular embodiment the process contains at least one bulkreactor zone and at least one gas phase reactor zone, each zonecomprising at least one reactor and all reactors being arranged incascade.

In one particularly preferred embodiment the polymerisation process forpolymerising olefins, in particular propylene optionally withcomonomers, like ethylene or other α-olefins, comprises at least onebulk reactor and at least one gas phase reactor arranged in that order.In some preferred processes the process comprises one bulk reactor andat least two, e.g. two or three gas phase reactors.

The process may further comprise pre- and post-reactors.

Prereactors comprise typically prepolymerisation reactors as alreadyexplained above. In these kinds of processes use of higherpolymerisation temperature (70° C. or higher, preferably 80° C. orhigher, even 85° C. or higher) either in some or all reactors of thereactor cascade, is preferred in order to achieve some specificproperties to the polymers. The new inventive method can be easilyscaled up in order to avoid common up-scaling problems in the prior artwhich led to unsatisfied catalyst morphology and particle sizedistribution as well as reduced activity at higher temperature.

The catalyst component according to the present invention has a highnucleating effect in polypropylene, which is of outmost importance whenpolypropylenes with improved stiffness-impact behaviour are desired.

Using the above described modified catalyst component for thepreparation of nucleated polypropylene thus provides nucleatedpolypropylene products comprising polymeric nucleating agents like polyvinyl compounds, with improved stiffness-impact balance/behaviour, dueto increased crystallinity (i.e. increase of the Crystallisationtemperature Tcr) of the produced polypropylene.

There is also an increase seen in the Melting Temperature (Tm) of thenucleated polypropylene produced with this catalyst composition.

In the following the present invention is further illustrated by meansof examples

Experimental Part

Test Methods

A. Measuring Methods

The following definitions of terms and determination methods apply forthe above general description of the invention including the claims aswell as to the below examples unless otherwise defined.

Quantification of Microstructure by NMR Spectroscopy

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used toquantify the isotacticity and regio-regularity of the propylenehomopolymers.

Quantitative ¹³C{¹H} NMR spectra were recorded in the solution-stateusing a Bruker Advance III 400 NMR spectrometer operating at 400.15 and100.62 MHz for ¹H and ¹³C respectively. All spectra were recorded usinga ¹³C optimised 10 mm extended temperature probehead at 125° C. usingnitrogen gas for all pneumatics.

For propylene homopolymers approximately 200 mg of material wasdissolved in 1,2-tetrachloroethane-d₂ (TCE-d₂). To ensure a homogenoussolution, after initial sample preparation in a heat block, the NMR tubewas further heated in a rotatary oven for at least 1 hour. Uponinsertion into the magnet the tube was spun at 10 Hz. This setup waschosen primarily for the high resolution needed for tacticitydistribution quantification (Busico, V., Cipullo, R., Prog. Polym. Sci.26 (2001) 443; Busico, V.; Cipullo, R., Monaco, G., Vacatello, M.,Segre, A. L., Macromolecules 30 (1997) 6251). Standard single-pulseexcitation was employed utilising the NOE and bi-level WALTZ16decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong,R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225;Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J.,Talarico, G., Macromol. Rapid Commun. 2007, 28, 11289). A total of 8192(8k) transients were acquired per spectra.

Quantitative ¹³C{¹H} NMR spectra were processed, integrated and relevantquantitative properties determined from the integrals using proprietarycomputer programs.

For propylene homopolymers all chemical shifts are internally referencedto the methyl isotactic pentad (mmmm) at 21.85 ppm.

Characteristic signals corresponding to regio defects (Resconi, L.,Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253; Wang,W-J., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, H. N.,Macromolecules 17 (1984), 1950) or comonomer were observed.

The tacticity distribution was quantified through integration of themethyl region between 23.6-19.7 ppm correcting for any sites not relatedto the stereo sequences of interest(Busico, V., Cipullo, R., Prog.Polym. Sci. 26 (2001) 443; Busico, V., Cipullo, R., Monaco, G.,Vacatello, M., Segre, A. L., Macromolecules 30 (1997) 6251).

Specifically the influence of regio-defects and comonomer on thequantification of the tacticity distribution was corrected for bysubtraction of representative regio-defect and comonomer integrals fromthe specific integral regions of the stereo sequences.

The isotacticity was determined at the pentad level and reported as thepercentage of isotactic pentad (mmmm) sequences with respect to allpentad sequences:[mmmm]%=100*(mmmm/sum of all pentads)

The presence of 2.1 erythro regio-defects was indicated by the presenceof the two methyl sites at 17.7 and 17.2 ppm and confirmed by othercharacteristic sites. Characteristic signals corresponding to othertypes of regio-defects were not observed (Resconi, L., Cavallo, L.,Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253).

The amount of 2.1 erythro regio-defects was quantified using the averageintegral of the two characteristic methyl sites at 17.7 and 17.2 ppm:P_(21e)=(I_(e6)+I_(e8))/2

The amount of 1.2 primary inserted propene was quantified based on themethyl region with correction undertaken for sites included in thisregion not related to primary insertion and for primary insertion sitesexcluded from this region:P₁₂I_(CH3)+P_(12e)

The total amount of propene was quantified as the sum of primaryinserted propene and all other present regio-defects:P_(total)=P₁₂+P_(21e)

The mole percent of 2.1 erythro regio-defects was quantified withrespect to all propene:[21e] mol.−%=100*(P_(21e)/P_(total))

MFR₂ (230° C.) is measured according to ISO 1133 (230° C., 2.16 kg load)

The xylene soluble fraction at room temperature (XS, wt.-%): The amountof the polymer soluble in xylene is determined at 25° C. according toISO 16152; 5^(th) edition; 2005-07-01.

DSC analysis, melting temperature (T_(m)) and heat of fusion (H_(f)),crystallization temperature (T_(c)) and heat of crystallization (H_(c)):measured with a TA Instrument Q200 differential scanning calorimetry(DSC) on 5 to 7 mg samples. DSC is run according to ISO 11357/part3/method C2 in a heat/cool/heat cycle with a scan rate of 10° C./min inthe temperature range of −30 to +225° C. Crystallization temperature(T_(c)) and heat of crystallization (H_(c)) are determined from thecooling step, while melting temperature (T_(m)) and heat of fusion(H_(f)) are determined from the second heating step.

ICP Analysis (Al, Mg, Ti)

The elemental analysis of a catalyst was performed by taking a solidsample of mass, M, cooling over dry ice. Samples were diluted up to aknown volume, V, by dissolving in nitric acid (HNO₃, 65%, 5% of V) andfreshly deionised (DI) water (5% of V). The solution was further dilutedwith DI water up to the final volume, V, and left to stabilize for twohours.

The analysis was run at room temperature using a Thermo Elemental iCAP6300 Inductively Coupled Plasma—Optical Emmision Spectrometer (ICP-OES)which was calibrated using a blank (a solution of 5% HNO₃), andstandards of 0.5 ppm, 1 ppm, 10 ppm, 50 ppm, 100 ppm and 300 ppm of Al,Mg and Ti in solutions of 5% HNO₃.

Immediately before analysis the calibration is ‘resloped’ using theblank and 100 ppm standard, a quality control sample (20 ppm Al, Mg andTi in a solution of 5% HNO₃ in DI water) is run to confirm the reslope.The QC sample is also run after every 5^(th) sample and at the end of ascheduled analysis set.

The content of Mg was monitored using the 285.213 nm line and thecontent for Ti using 336.121 nm line. The content of aluminium wasmonitored via the 167.079 nm line, when Al concentration in ICP samplewas between 0-10 ppm (calibrated only to 100 ppm) and via the 396.152 nmline for Al concentrations above 10 ppm.

The reported values are an average of three successive aliquots takenfrom the same sample and are related back to the original catalyst byinputting the original mass of sample and the dilution volume into thesoftware.

The amount of residual VCH in the catalyst/oil mixture was analysed bygas chromatography. Toluene was used as internal standard.

Chemicals Used in the Examples:

2-ethyl-hexanol—CAS no 104-76-7

propylene glycol butyl mono ether—CAS no 5131-66-8, provided bySigma-Aldrich

bis(2-ethylhexyl) citraconate—CAS no 1354569-12-2

Necadd 447—provided by M-I SWACO

Viscoplex 1-254—provided by RohMax Additives GmbH

diethyl aluminum chloride—CAS no 96-10-6, provided by Witco

EXAMPLES Example 1

1a) Catalyst Preparation

3.4 litre of 2-ethylhexanol and 810 ml of propylene glycol butylmonoether (in a molar ratio 4/1) were added to a 20 l reactor. Then 7.8litre of a 20% solution in toluene of BEM (butyl ethyl magnesium)provided by Crompton GmbH were slowly added to the well stirred alcoholmixture. During the addition the temperature was kept at 10° C. Afteraddition the temperature of the reaction mixture was raised to 60° C.and mixing was continued at this temperature for 30 minutes. Finallyafter cooling to room temperature the obtained Mg-alkoxide wastransferred to storage vessel.

21.2 g of Mg alkoxide prepared above was mixed with 4.0 mlbis(2-ethylhexyl) citraconate for 5 min. After mixing the obtained Mgcomplex was used immediately in the preparation of catalyst component.

19.5 ml titanium tetrachloride was placed in a 300 ml reactor equippedwith a mechanical stirrer at 25° C. Mixing speed was adjusted to 170rpm. 26.0 of Mg-complex prepared above was added within 30 minuteskeeping the temperature at 25° C. 3.0 ml of Viscoplex 1-254 and 1.0 mlof a toluene solution with 2 mg Necadd 447 was added. Then 24.0 ml ofheptane was added to form an emulsion. Mixing was continued for 30minutes at 25° C. Then the reactor temperature was raised to 90° C.within 30 minutes. The reaction mixture was stirred for further 30minutes at 90° C. Afterwards stirring was stopped and the reactionmixture was allowed to settle for 15 minutes at 90° C.

The solid material was washed 5 times: Washings were made at 80° C.under stirring 30 min with 170 rpm. After stirring was stopped thereaction mixture was allowed to settle for 20-30 minutes and followed bysiphoning.

Wash 1: Washing was made with a mixture of 100 ml of toluene and 1 mldonor

Wash 2: Washing was made with a mixture of 30 ml of TiCl4 and 1 ml ofdonor.

Wash 3: Washing was made with 100 ml toluene.

Wash 4: Washing was made with 60 ml of heptane.

Wash 5. Washing was made with 60 ml of heptane under 10 minutesstirring.

Afterwards stirring was stopped and the reaction mixture was allowed tosettle for 10 minutes decreasing the temperature to 70° C. withsubsequent siphoning, and followed by N₂ sparging for 20 minutes toyield an air sensitive powder.

1b) VCH modification of the catalyst

−35 ml of mineral oil (Paraffinum Liquidum PL68) was added to a 125 mlstainless steel reactor followed by 0.82 g of triethyl aluminium (TEAL)and 0.33 g of dicyclopentyl dimethoxy silane (donor D) under inertconditions at room temperature. After 10 minutes 5.0 g of the catalystprepared in 1a (Ti content 1.4 wt %) was added and after additionally 20minutes 5.0 g of vinylcyclohexane (VCH) was added.). The temperature wasincreased to 60° C. during 30 minutes and was kept there for 20 hours.Finally, the temperature was decreased to 20° C. and the concentrationof unreacted VCH in the oil/catalyst mixture was analysed and was foundto be 120 ppm weight.

1c) Polymerisation—Inventive Example 1

41 mg of donor D (TEAL/Donor ratio 10 mol/mol) and 206 mg of TEAL(TEAL/Ti ratio 250 mol/mol) was mixed with 30 ml of pentane. Donor totitanium was 25 mol/mol. Half of this mixture was added to the 5 litrestirred reactor and half was added to 209 mg of the oil/catalyst mixture(=124.7 mg of dry catalyst). After 10 minutes thepentane/catalyst/TEAL/donor D mixture was added to the reactor, followedby 300 mmol H2 and 1.4 kg of propylene at room temperature. Thetemperature was increased to 80° C. during 16 minutes and was kept atthis temperature for 1 hour. Unreacted propylene was flashed out byopening the exhaust valve. The reactor was opened and the polymer powderwas collected and weighed.

MFR, isotacticity, crystallisation properties and stiffness of thepolymer is shown in table 2.

Comparative Example 1

In this example the same catalyst as in example 1 was used, but thecatalyst was used as such without VCH modification of the catalyst. 43mg of catalyst was used and the hydrogen amount was 170 mmol, butotherwise the polymerisation conditions were the same as in example 1.

From table 2 it is seen that the VCH modified catalyst (Inv.Ex. 1) hasabout 10° C. higher crystallisation temperature than the catalystwithout VCH modification (Comparative example Comp.Ex 1)

Comparative Example 2

C2a) Comparative Catalyst Preparation

First, 0.1 mol of MgCl₂×3 EtOH was suspended under inert conditions in250 ml of decane in a reactor at atmospheric pressure. The solution wascooled to the temperature of −15° C. and 300 ml of cold TiCl₄ was addedwhile maintaining the temperature at said level. Then, the temperatureof the slurry was increased slowly to 20° C. At this temperature, 0.02mol of dioctylphthalate (DOP) was added to the slurry. After theaddition of the phthalate, the temperature was raised to 135° C. during90 minutes and the slurry was allowed to stand for 60 minutes. Then,another 300 ml of TiCl₄ was added and the temperature was kept at 135°C. for 120 minutes. After this, the catalyst was filtered from theliquid and washed six times with 300 ml heptane at 80° C. Then, thesolid catalyst component was filtered and dried. Catalyst and itspreparation concept is described in general e.g. in patent publicationsEP491566, EP591224 and EP586390.

C2b) VCH Modification of the Catalyst

This example was done in accordance with Example 1b, but as catalyst wasused a phthalate containing catalyst prepared according to example C2a,Ti content 1.8 wt %. 52 ml of oil, 1.17 g TEAL, 0.73 g donor D wereused. The reaction temperature was 65° C. with this catalyst. Theconcentration of unreacted VCH in the final catalyst was 200 ppm weight.The concentration of unreacted VCH is almost twice as high with thisphthalate containing catalyst, despite the higher reaction temperature,as with the phthalate free catalyst described in example 1b.

C2c) Polymerisation

Polymerisation was done in accordance to example 1, but using thecatalyst prepared in this comparative example. 22 mg of donor D, 176 mgof TEAL and 84.4 mg of the oil/catalyst mixture was used, giving a donorto titanium ratio of 25 mol/mol. 620 mmol of hydrogen was used.

In Table 1 the VHC conversion of Inventive Ex. 1 and Comparative Ex. 2are compared. In Table 2 the catalysts of Inventive Ex. 1 andComparative Ex. 1 and the produced polymers are compared.

TABLE 1 VCH conversion Inv. Comp. Ex. 1 Ex. 2 Residual VCH [ppm] 120 200Activity [kgPP/gcath] 31 69 MFR [g/10 min] 16 20

TABLE 2 Polymer properties Inv. Comp. Ex. 1 Ex 1 Activity [kgPP/gcath]31 18 MFR [g/10 min] 16 7.5 mmmm [%] 97.5 97.8 Tc [° C.] 128.2 117.4 Tm[° C.] 167.3 164.5 Crystallinity [%] 52.2 51.9 Flexural modulus [Mpa]1990 1680

From table 1 it can be seen that the in reactor nucleated phthalate freecatalyst used in example 1 gives very high conversion rate, especiallyseen in the lower amount of residual VCH.

From Table 2 it can be seen that the activity of the phthalate freecatalyst significantly improves by about 70% due to the presence of thenucleating agent.

The invention claimed is:
 1. Process for the production of a nucleatedpolypropylene composition, comprising: A) obtaining a catalystcomposition containing a catalyst component through the steps of: a1)providing a solution of at least a Group 2 metal alkoxy compound (Ax)being the reaction product of a Group 2 metal compound (MC) and amonohydric alcohol (A) comprising in addition to the hydroxyl moiety atleast one ether moiety optionally in an organic liquid reaction medium;or a2) providing a solution of at least a Group 2 metal alkoxy compound(Ax′) being the reaction product of a Group 2 metal compound (MC) and analcohol mixture of the monohydric alcohol (A) and a monohydric alcohol(B) of formula ROH, optionally in an organic liquid reaction medium; ora3) providing a solution of a mixture of the Group 2 metal alkoxycompound (Ax) and a Group 2 metal alkoxy compound (Bx) being thereaction product of a Group 2 metal compound (MC) and the monohydricalcohol (B), optionally in an organic liquid reaction medium; or a4)providing a solution of Group 2 metal alkoxy compound of formulaM(OR1)_(n)(OR2)_(m)X_(2−n−m) or mixture of Group 2 alkoxidesM(OR1)_(n′)X_(2−n′) and M(OR2)_(m′)X_(2−m′), where M is Group 2 metal, Xis halogen, R1 and R2 are different alkyl groups of C2 to C16 carbonatoms, and 0<n<2, 0<m<2 and n+m+(2−n−m)=2, provided that both n and m≠0,0<n′<2 and 0<m′<2; and b) adding said solution from step a1, a2, a3, ora4 to at least one compound (TC) of a transition metal of Group 4 to 6,and c) obtaining the solid catalyst component particles, d) washing saidsolidified particles, e) recovering the solidified particles of theolefin polymerisation catalyst component, wherein an electron donor isadded at any step prior to step c) and is a non-phthalic internalelectron donor, wherein the catalyst component is washed in step d) atleast three times with at least one toluene and at least one TiCl₄washing step and 1 to 3 further washing steps with an aromatic and/oraliphatic hydrocarbon selected from toluene heptane, or pentane; whereininternal donor is added to either the toluene washing step and/or theTiCl₄ washing step in an amount of 10 to 60 wt % of the total amount ofdonor used in catalyst preparation steps a) to d); wherein the catalystcomponent is further modified by a polymeric nucleating agent comprisingvinyl compound units, and wherein the catalyst modification is performeduntil the concentration of unreacted vinyl compound is less than 0.1 wt%; and B) polymerizing propylene, optionally with co-monomers selectedfrom C2 or C4 to C12 monomers in the presence of the catalystcomposition obtained from step A), wherein the nucleated polypropylenecomposition comprises a polymeric nucleating agent in an amount in therange from 15 to 500 ppm.
 2. The process according to claim 1, whereinthe polymeric nucleating agent is selected from the group of vinylalkanes or vinyl cycloalkanes, 3-methyl-1-butene, 3-ethyl-1-hexene,3-methyl-1-pentene, 4-methyl-1-pentene or mixtures thereof.
 3. Theprocess according to claim 1, wherein the internal donor (ID) used inthe preparation of the catalyst component is selected from (di)esters ofnon-phthalic carboxylic (di)acids, 1,3-diethers, derivatives andmixtures thereof.
 4. The process according to claim 3, wherein theelectron donor for the catalyst component is selected from diesters ofmono-unsaturated dicarboxylic acids, belonging to the group comprisingmalonates, maleates, succinates, citraconates, glutarates,cyclohexene-1,2-dicarboxylates and benzoates, and any derivatives and/ormixtures thereof.
 5. The process according to claim 1, wherein thecatalyst composition comprises the modified catalyst component togetherwith a co-catalyst and an external donor for the polymerization ofpropylene, optionally with co-monomers selected from C2 or C4 to C12monomers.